sundance-communications.com/forum Forums TDM Business Telephone Systems Vodavi Telephones & Systems STSe PRI

Ok Im in somewhat of a pickle. lol I have a pri going into my system. I have the T1 card installed and all other boards needed. I have programed all the stuff that is needed for the pri according to the manual (not that the manual has that much info). The pri provider is saying that when they call the first number in the pri the system picks up and all is fine. But call that number again the system pics up and there is dead air. They are saying something is wrong with the b-channel. Im not 100% sure what that means. I wasnt aware of having to program anything for the b-channel in the phone. Any help would be appreciated.

Thanks

In strict regards to the PRI circuit-

Dead-air calls are a strong indicator of one or more bad PRI B-channels. However, most dead-air call symptoms I've encountered have occurred intermittently, because they're associated with only the calls that attempt to process across the same faulty B channel(s).

Regardless, this is a problem that needs be addressed and corrected by the PRI's provider. Sometimes it can be accomplished by the provider simply removing the DS1 facility from service, then restoring it back to in-service. Other times the provider may have to either completely delete each B-channel individually (we call it tearing down the PRI), and individually reassign them back to the PRI, or busy each channel out manually one at a time, while placing numerous test calls to isolate the bad channel(s), then delete and reassign those channels back to the PRI.

The toughest part about dead-air/bad B-channel symptoms, is that (at least in a Lucent 5ESS) many times the "bad" B-channels appear fine on output reports from the switch. That's why I mentioned the possible need for the provider to isolate the bad channels thru manually busying them out one at a time, and placing test calls. The PRI provider should understand how to do this, and it shouldn't take very long for this to get corrected. I've never encountered a dead-air symptom that impacted the entire PRI after the first call processed. It was always "intermittent" and usually it never resulted in more than a couple to a few bad channels at most.

You'll need to try resetting each channel using the CONFIG utility to confirm that they are all clear.

Ok so went to site today. Called the same first DID in the group with 4 cell phones and they all rolled no problem. Heres the million dollar question. Can you call out using the same pri group to call in and test the pri?? Meaning can you use a system phone and dial the first number in the pri and have the phones ring. Thats the only time I got dead air. Any other time it worked like it was supposed to.

I'd recommend placing separate test calls for either direction, using different sources and destinations.

From the way you're describing this test, it sounds like you could be forcing a 'glare' condition that can neither control or yield a specific B-channel, thus resulting in your hearing the constant silence.

Glare occurs when two simultaneous calls from oppisite directions on the same 2-way PRI are attempting to process, but they colide on the same B-channel. To avoid this, calls across two-way PRIs normally hunt for available B-channels from either "low-to high" members based on their direction, or vice-versa, and PRIs are also set up to allow calls from one specific direction to either take control of the B-channel, or yield that channel to the opposite directed call if glare occurs.

That's my best speculation without reviewing an IPCT (in-progress call trace) while the dead-air is being heard.

But that is something on the clec's side correct?

Yes. You stated that the calls are processing fine. As far as testing inbound in the future, I still recommend to use only source telephone numbers that originate beyond your PRI (opposite your system) for placing inbound test calls.

Thanks for the help Mike.

You also may have to put the trunks that you are calling out may have to have them in group 0
you may only have 12 trunks not 24 trunks on your PRI Circuit